| T-00:02.4 |
Engine Start |
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Atlas booster and sustainer engines are ignited and undergo checkout prior to liftoff. The two ground-start boosters will light a half-second before launch. |
|
| T+00:00 |
Launch |
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Rocket lifts off and begins a vertical rise away from SLC-3E at Vandenberg Air Force Base. |
|
| T+00:08 |
Roll Program |
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Atlas begins a seven-second roll maneuver to align itself with proper flight azimuth. Following the roll, the vehicle begins open-loop pitch and yaw steering under control of the Centaur inertial guidance system. |
|
| T+00:59 |
Air-lit SRB Ignition |
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The remaining two solid rocket boosters strapped to the Atlas are ignited once onboard computer software determines the two ground-start SRBs have burned out. |
|
| T+01:44 |
Jettison Ground-Lit SRBs |
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The two spent solid rocket boosters that were ignited on the ground are jettisoned to fall into the Pacific Ocean. SRB separation does not occur until the Atlas travels far enough downrange so the boosters land in the allowed Range Safety impact area. |
|
| T+01:58 |
Jettison Air-Lit SRBs |
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Computer software will determine the air-start solid rocket boosters have burned all their propellant and should be jettisoned from the Atlas vehicle. The two SRBs will fall into the Pacific Ocean. |
|
| T+02:46 |
Booster Engine Cutoff |
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BECO occurs when axial acceleration of 5.0 g is obtained. Sustainer engine provides the continued boost toward orbit for the Atlas rocket. |
|
| T+02:49 |
Jettison Booster Package |
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The bottom engine structure is separated from the Atlas vehicle. |
|
| T+03:11 |
Jettison Payload Fairing |
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The 14-foot diameter aluminum payload fairing that protected the Terra spacecraft during launch is separated once heating levels drop to predetermined limits. |
|
| T+04:42 |
Sustainer Engine Cutoff |
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SECO is commanded once minimum residual propellant is sensed inside the Atlas booster stage. |
|
| T+04:44 |
Atlas/Centaur Separation |
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Two seconds after the Atlas sustainer engine shuts down, the Atlas booster stage separates from the Centaur upper stage. |
|
| T+05:01 |
Centaur Main Engine Start |
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The single Centaur burn of AC-141 will consist of a 369-second duration firing of the two upper stage engines to inject the combined Centaur and Terra spacecraft into required low-Earth orbit. |
|
| T+11:10 |
Centaur Main Engine Cutoff |
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The rocket's guidance system will command Centaur cutoff once the proper orbit has been reached. During the burn, guidance steering should have achieved an orbital inclination of 98.31 degrees. |
|
| T+11:13 |
Start Alignment for Separation |
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The Centaur will orient itself to the correct position for deployment of Terra into space. |
|
| T+13:40 |
Spacecraft Separation |
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Terra, the flagship of NASA's Earth Observing System, is released from the Centaur upper stage to complete the launch. |
